I'm happy about Deadpool and X-Force films but what I'd really like to see is an X-Factor spin-off.

Just like how Colossus never joined the X-Men in the new timeline in X-Force, this version of X-Factor would have had Cyclops and Phoenix having never been X-Men and instead a team set up by the military to investigate threats to mutantkind. That and Phoenix never had her dark side blocked, she's now fully in control of it which both makes her a lot more proactive but also at times overwhelmed by how powerful she is and sees her powers as more of a burden than a gift after she accidentally murdered somebody as a teenager.

From the first X-Factor in addition to Cyclops and Jean we'd have Angel who never got enough development in X3. From the second X-Factor I'd bring in Forge along with Multiple Man. From the third I'd use Siryn. From the fourth comes Gambit. That's seven characters which is the same amount as in the main team in the first film.

Also, in this timeline, Gambit died and was cloned by Sinister. He lacks memories of his previous life but begins the film as a villain employed to help Sinister carry out a harvest of the Morlocks' DNA.

The storyline used would be Mutant Massacre that would start a rivalry between Cyclops and Sinister, have Gambit be redeemed and Angel dies and is brought back as a clone by Apocalypse after the credits.

Sinister's agenda is to prevent Apocalypse from taking over the world by any means necessary, no matter how monstrous. Eventually he and Cyclops would be forced to team up to stop Apocalypse despite them absolutely hating each other.

And when it comes to cameos, Wolverine would appear having been sent by Xavier to investigate and he gets a fight in with Sabertooth, while appearing jealous that Cyclops and Jean are married as he remembers the old timeline. Cable from X-Force would be the second cameo who's hinted to be the son of Cyclops but that won't happen just yet.

The X-Men proper in the new timeline should be Beast, Storm, Wolverine, Nightcrawler, Shadowcat, Iceman, Xavier and Rogue.